The inheritance of variability in the behavioral and physiologic effects of psychopharmacologic agents in clinical use will be studied. The initial project will be on pharmacogenetics of d-amphetamine. Heritability and intra-individual stability of pharmacokinetic data and of the following parameters of response will be determined: 1) behavioral ratings 2) adrenergic receptor response 3) neuroendocrine response and 4) cortical evoked response.